Researchers have said that up to 1 in 5 women with breast cancer could benefit from a type of treatment currently only given to patients with a rare form of the disease caused by gene mutations. According to a new study, medications designed to treat less common cases of breast cancer driven by faults in tumour-suppressing BRCA genes may also help women with more common forms of the disease. Scientists from the Wellcome Trust Sanger Institute found around 8,000 more patients may respond to the medications than are currently receiving them.
Around 1% to 5% of the the 55,000 women diagnosed with breast cancer annually in the UK are believed to have BRCA-driven disease. The researchers said thousands of more common forms of breast cancers were biochemically similar to these rarer cases involving BRCA1 and BRCA2 gene mutations. Lead researcher Dr Serena Nik-Zainal stated, “Our study shows that there are many more people who have cancers that look like they have the same signatures and same weakness as patients with faulty BRCA1 and BRCA2 genes.”
Dr Nik-Zainal said these women may respond to a class of medications known as PARP inhibitors that are are specifically designed to target tumours with the defective genes. She said, “We should explore if they could also benefit from PARP inhibitors.” The team, whose results are published in the journal Nature Medicine, analysed DNA from breast cancer tissue samples taken from 560 patients. A piece of computer software called HRDetect was used to identify genetic code “fingerprints” revealing biochemical pathways like those correlated with mutant BRCA1 and 2 genes.
Of the total group of patients, 22 had previously diagnosed BRCA 1 and 2 mutations. Another 55 had unexpected BRCA mutations, including some very unusual ones that were not inherited. Another 47 had BRCA genes with no recognised mutations. However, in these patients the repair mechanisms controlled by the genes were still faulty. Dr Nik-Zainal stated, “It’s possible there are other ways of turning off BRCA 1 and 2 that we don’t understand, perhaps involving other genes.” She continued, “PARP inhibitors are important for quality of life because they specifically target cancer cells and so are well tolerated.”